Fuse construction



N0 2, 1943- H. A. TRIPLETT FUSE CONSTRUCTON Original Filed NOV. 13, 1939 3 SheebS-Sheet l NOV 2, 194,3 l-LA. TRIPLETT FUSE CONSTRUCTION Original Filed Nov. 13, 1939 3 Sheets-Sheet 2 Nov. 2, 1943. H, A. TRIPLETT 2,333,217 l FUSE CONSTRUCTION Original Filed Nov. l5, 1939 3 Sheets-Sheet 5 Patented Nov. 2, 1943 FUSE CONSTRUCTION Hugh A. Triplett, Wilmette, Ill., assigner to Schweitzer & Conrad, Inc., Chicago, Ill., a corporation of Delaware Original application November V13, 1939, Serial No. 304,035. Divided and this application June 5, 1942, Serial No. 445,892

6 Claims.

My invention relates, generally, to circuit interrupters and it has particular relation to fuse devices of the dropout type. This application is a division of my copending application Serial No. 304,035, filed November 13, 1939.

An object of myv invention is to provide simple and eflicient meansfor latching a fuse cartridge in place in a fuse tube.

Another object `of my invention is to provide for latching the fuse cartridgein place by interaction with the same of a single spring biased latch pin which is movable transversely of the longitudinal axis of thecartridge.

Other objects vof my invention will, in part, be obvious and in part appear hereinafter.

Accordingly, my invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings in which:

Figure 1 is a view, in side elevation, of a dropout fuse device constructed in accordance with my invention;

Figure 2 is a view, in front elevation, of the fuse device shown in Figure 1;

Figure 3., is a view, in side elevation, of the lower contact assembly for the fuse device shown in Figure 1;

Figure 4 is a View, in front elevation, of the contact assembly shown in Figure 3;

Figure 5 is a View, partly in side elevation and partly in section, of the upper contact assembly forvthe fuse device shown in Figure 1;

Figure 6 is a View, in bottom plan, of the contact assembly shown in Figure 5; and

Figures 7A and 7B, taken together, show the construction of the dropout fuse tube and associated parts, certain portions being broken away in order to more clearly illustrate the details of construction.

Referring now particularly to Figures 1 and 2 of the drawings, it will be observed that the ref- @rence character designates, generally, a dropout fuse having a channel base I2 on which.y are mounted insulators |3 and I4. Upper and lower contact assemblies I5 and I6 are mounted on the insulators I3 and I4 and they are provided,

respectively, with circuit terminal members I'I and I8 to permit clamping thereto of the line conductors. A fuse tube, shown generally at 20, is provided with upper and lower terminal assemblies 2| and 22. The upper terminal assembly 2| is arranged to have contact engagement with the upper stationary contact assembly 4I5 While the lower terminal assembly 22 is arranged not only to have contact engagement with the lower Contact assembly I5 but is also hingedly mounted thereon. When a fuse link Jor fuse cartridge within the fuse tube 20 blows, as will be described hereinafter, the upper terminal assembly 2| is no longer held in the position shown in Figures 1 and 2 of the drawings but is released therefrom to permit the fuse 20 to rotate to the alter nate position shown by the broken lines. This provides a definite air gap between the circuit terminals formed by the contact assemblies I5 and I5 so that it is unnecessary to rely upon the gap which is provided by blowing of the fuse link or fuse cartridge itself.

In Figures 5 and 6 of the drawings the details of construction of the upper contact assembly I5 are more clearly shown. The upper contact assembly I5 is provided with a frame member 25 that is arranged to be suitably mounted on the insulator I3. It has integrally formed therewith a sleet hood 26 which serves to protect the mechanism underneath including the upper terminal assembly 2| of the fuse tube -20 from the elements. Guide clips 2l are secured, as illustrated, to the opposite side walls of the sleet hood 26 for guiding the fuse tube 20 to the circuit closed position.

Flexible and resilient Contact fingers 23 are provided with out and upwardly turned end portions 29 for contact engagement with the spaced apart contact surfaces on contact bosses 3D, Figure 7A, forming a part of the upper terminal 2| of the fuse tube 2B. As will hereinafter appear, a portion of this upper terminal assembly 2| moves upwardly when the device is called upon to interrupt the circuit and, therefore, the outer ends 29 of the contact fingers 28 and the Contact surfaces of the contact bosses 3i] are shaped as described to facilitate this movement. At their inner ends the contact ngers 28 `are secured, as by rivets, 3|, to the depending sides 32 of a backing member, shown generally at 33. A hinge pin 34 extending through the depending sides 32 of the backing member 33 and into the depending side walls of the sleet hood 26 serves to rockably mount the backing member 33 and the parts carried thereby. A limited degree of freedom of vertical movement in the contact fingers 28 is thereby provided. It will be observed that the outer end portions of the sides 32 of the backing member 33 are turned outwardly and upwardly to correspond to the outer end portions 29 of the contact fingers 28. Coil compression springs 36 are provided therebetween for biasing the end portions 29 into contact engagement with the contact surfaces of the contact bosses 30, Figure 7A, of the upper terminal assembly 2|.

It will now be apparent that the contact fingers 28 have two degrees of freedom. Because of their being rockably mounted on the pin 34, they are movable in a Vertical plane. The inherent resiliency of the contact fingers 28 and the springs 36 permit movement in a horizontal plane. As a result close alignment is not required to be maintained between the fuse tube 20 or its mounting in the lower contact assembly I6 and the upper contact assembly I5. This is of considerable advantage not only from a manufacturing but also from an operating standpoint. It is not necessary to provide for mounting the lower terminal assembly 22 of the fuse tube 20 in the lower contact assembly I6 with close tolerances. In the field it is unnecessary to hold the insulators I3 and I4 within close limits of tolerance nor must a great deal of care be eX- ercised in operating the fuse tube 2|J to the circuit closed position. When itis recalled that fuse devices of the type disclosed herein are mounted overhead and are intended to be operated by means of switch hooks from a considerable distance, the advantages of these features will be readily apparent.

It is desirable to automatically align the contact fingers 28 with the contact bosses 30, Figure 7A. For this purpose a centering arm 39 is integrally formed with one of the sides 32 of the backing member 33 and is pro-vided with a slotted opening 4I), the outer ends of which are flared outwardly, as illustrated in Figure 5, for receiving a guide pin 4 I, Figure 7A, that is carried by a guide arm 42 forming a part of the upper terminal assembly 2| of the fuse tube 2U. When the fuse tube 20 is operated toward the closed circuit position, the guide pin 4I first enters the ared out end portion of the slot and then enters the slot 40 itself to lift the backing member 33 to the extent that may possibly be required. Since there is a definite relationship between the positions of the guide pin 4I and the contact bosses 3U and also between the slot 40 and the contact fingers 28, it will be readily apparent that proper contact engagement will be made between the outer end portions 2!! of the contact fingers .'28 and the contact surfaces of the contact bosses 3U despite the fact that they might otherwise be considerably out of alignment. The contact surfaces of the outer end portions 2S which are inclined from straight vertical surfaces have a tendency, when pushed in, or as a result of standing in a closed position over a long period of time and being subjected to vibration, etc., to change their relation to each other in a vertical direction. This tendency becomes greater, of course, as the insulation stacks I3 and I4 become higher. It will be noted that the centering arm 33 holds the two contact fingers 28 in a xed vertical relation with respect to each other after the fuse tube 2l) is pushed into place.

With a view to holding the fuse tube 20 in the circuit closed position, a latch arm 43 is provided, Figure 5, that is secured at its rear end by rivets 44 t0 a bridging member 45 between the sides 32 of the backing member 33. The forward end of the latch arm 43 is split and the two portions thereof are turned at right angles to the remainder of the latch arm 43 as indicated at 46 for receiving therebetween a roller 41. A spring strip 48, secured in position by the rivets 44 which also hold the latch arm 43, serves to bias the roller 41 upwardly, its upward movement being limited by a stop 49 formed by a depending flange of the backing member 33. It will be understood that the roller 41 is adapted to be engaged by a latch hook 50, Figure 7A, forming a part of the upper terminal assembly 2| of the fuse tube 20. Since the latch arm 43 and the roller 41 carried thereby move with the backing member 33, the roller 41 is automatically centered with the latch hook 50 when the guide pin 4| enters the slot 40 in the centering arm 39.

In order to provide a good electrical connection between the backing member 33 and the frame 25 a flexible shunt 5I is provided comprising several layers of flexible copper strips. The flexible shunt 5I is secured at one end by rivets 52 to a bridging member 53 between the sides 32 of the backing member 33. At its other end it is secured to the frame 25 by rivets 54.

The downward movement of the backing member 33 and the parts carried thereby about the hinge pin 34 is limited by a stop 55. It will be noted that the stop 55 is provided by a lug that may be cast integrally with one of the side walls of the sleet hood 26.

In Figures 3 and 4 of the drawings the details of construction of the lower contact and hinge assembly I6 are illustrated. The assembly comprises a housing that is open at the front and has a wall 6I closing the top and side walls 62 depending therefrom. A rear wall 63 joins the walls 6I and 62, as shown. The assembly I6 serves not only to rockably mount the fuse tube 20 but also to conduct current to the lower terminal assembly 22.

In order to rockably mount the fuse tube 20, the side walls 62 are provided with slotted openings 64 for receiving therein trunnions, one of which is shown by a broken line at 65 in Figure '1B of the drawings as forming a part of the lower terminal assembly 22. When the fuse link or cartridge within the fuse tube 20 blows, the fuse tube 20 is unlatched at its upper end, as previously described, and rotates downwardly with the trunnions 65 turning in the bottoms of the slots 64. A rubber bumper 66 is provided for cushioning the inward swing of the fuse tube 20.

Disengagement between the fuse tube 20 and the hinge and contact assembly I6 is prevented by interfitting anges 61 and 68. The flanges 61 are formed integrally with the side walls 62 and project inwardly therefrom While the flanges 68, one of which is shown by broken lines in Figure 7B, are integrally formed with the lower terminal assembly 22. It; will be understood that, when the fuse tube 20 is in the circuit-closed position, the flanges 61 and 68 overlap, thereby preventing the recoil resulting from the blowing of the fuse link or cartridge causing the fuse tube 20 to move upwardly and possibly carry the trunnions 65 out of the slots 64. It is only when the fuse tube 20 has rotated to the broken line position shown in Figure 1 that it is possible to lift it out of the slots 64. Likewise, it can only be inserted therein by being initially placed substantially in this position.

Contact engagement with the lower terminal assembly 22 is provided by an inverted U-shaped contact finger 69 that may be secured by rivets 10 to therear wall 63 of the housing `68, which pass through one leg thereof. As shown, the outer end of the other leg of the U-shaped contact finger 69 is turned back on itself as indicated at 1| to provide a curved surface for contact engagement with a contact shoe 12, Figure 7B, that is part of a Contact arm 13 which extends from the lower terminal assembly 22 into the housing 68 when the fuse tube 28 is in the circuit closed position. An inverted U-shaped spring strip 18, conforming generally to the shape of the Contact nger 89 and having one leg commonly secured to the rear wall 63 therewith by the rivets 18, is pro vided for biasing the other leg of the contact finger 69 outwardly into contact engagement with the contact shoe 12. While the contact finger E9 itselfV is resilient, the added resiliency of the spring strip 14 serves to bias the portion 1| into high pressure contact engagement with the contact shoe 12.

While it is desirable to bias the Contact finger 69 into high pressure contact; engagement with the contact shoe 12, it is desirable that there be little movement of the turned back portion 1| required for effecting this high pressure Contact engagement. Therefore, a pin 18 is provided through the turned back portion 1|, its ends be ing secured in the side walls 82. rl`he contact finger 69 and the spring strip 11i are then held in a prestressed condition when the contact shoe 12 is out of engagement therewith. In order to obtain thefull biasing effect of the Contact finger 69 and of the spring strip 14, it is only necessary for the contact shoe 12 to move the turned back portion 1| out of engagement with the pin 18. Despite the faci-l that only a slight movement ci the contact finger 69 takes place, yet, as soon as it is moved away from the pin 16, the full biasing force of the contact nger 88 and of the spring strip 14 is available for providing the desired high pressure contact engagement. With a view to increasing the flexibility of the contact finger 69 and of the spring strip 14 they are split as indicated at 11 in Figure 4 of the drawings.

In Figures 7A and 'IB of the drawings the details of construction of the fuse tube 28 are shown. It will be observed that it comprises an outer sleeve 88 and a lining or inner sleeve 8|. Preferably, the outer sleeve 88 is formed of a weather resisting material, such as phenolic condensation product, while the liner or inner sleeve 8| is formed of fiber for reasons now well known to those skilled in the art. If desired, the liner or inner sleeve 8| may be omitted and the outer sleeve 88 alone used. A replaceable fuse cartridge, shown generally at 82, and described in detail in the application of which this is a division, is provided at the lower end oi the fuse tube 28 and connection thereto is provided by a flexible cable 83. A coil tension spring 84 is provided for tensioning the fuse cartridge 82 and withdrawing a terminal therefrom as will presently appear.

At their upper ends the exible cable 83 and the spring 84 are secured to a cable and spring fastener having a flanged head 85, the under surface of which engages a flange 86 of a sleeve 81 that is slidably mounted on a ferrule 88. A cap 89 is threaded on the sleeve, as shown, for clamping the flanged head 85 to the sleeve 81 for securing good electrical contact engagement therebetween. A spring 98, around the upper end of the fuse tube 20 and interposed between the sleeve 81 and the f-errule 88 serves to bias the former upwardly.

It will be noted that the contact bosses 38 and the latch hook 50v are formed integrally with the sleeve 81. As long as the fuse cartridge 82 remains intact, the sleeve 81 is prevented from moving upwardly under the influence of the coil spring 98. However, as soon as the fuse cartridge 82 blows, the sleeve 81 is no longer restrained but moves upwardly carrying with it the latch hook 58. As previously described, when it moves out of engagement with the roller 41, Figure 6, the fuse tube 28 is then free to swing downwardly to the circuit open position. The upward movement of the sleeve 81 relative to the ferrule 88 is limited by screws 9| which project into suitable slots, not shown, in the ferrule 88. The ferrule 88 is fastened on to the upper end of the fuse tube 20 so that it is rigid therewith. For this purpose transverse pins, one of which is shown at 94, are provided on opposite sides. Thus the guide arm 82, which is integrally formed with the ferrule 88, and the guide pin 8| are rigid with the fuse tube 20.

In order to lift the latch hook 58 from engagement Withthe roller 41 for the purpose of manually removing the fuse tube 28, a pair of arms are provided, one of which is shown at 85, on opposite sides of the ferrule 88 as a part of an operating lever 96 which is pivoted on a pin 91 that extends through a portion of the ferrule 88, as shown. An eye 98 isformed integrally with the operating arm 96 and is adapted to be engaged by the prong of a switch hook, as will be readily understood. A stop 99, forming a part of the eye 88, on engaging a flange |88 extending from the sleeve 81, serves to prevent upward movement `of the latter when the fuse tube 28 is moved to the closed circuit position.

In Figure '1B the details of construction of the lower terminal assembly 22 are more clearly illustrated. This terminal assembly includes a ferrule |83 that is fiXedly secured to the lower end of the fuse tube 20 by suitable means. An

' eye |85 is integrally formed with the ferrule |83 to receive the prong of a switch hook for placing the fuse 2'8 in position with the trunnions 65 in the slots 68. lt will be understood that the fuse tube is first positioned as shown by the broken lines in Figure l.. The prong of the switch stick is then removed from the eye |85, and placed in the eye 98. The fuse tube 28 is then swung upwardly to the circuit closed position.

It will be observed that the lower end of the i fuse cartridge 82 is provided with a recess in the form of a peripheral groove |81 with which a latch pin |88 cooperates to hold the fuse cartridge 82 in place in the lower end of the fuse tube 28 and within the ferrule |83 against the tension force of the coiled spring 84. The latch pin |88 is slidably mounted in an opening |89 which extends downwardly and through the lower end of the ferrule |83 in a suitably integrally formed boss. A fitting ||8 is threaded in the lower end of the opening 89 to provide for guiding the latch pin |88 in its movement. 'I'he latch pin |88 is biased inwardly so that the inner end interts with the groove |81 by a coil compression spring which reacts between the inner end of the fitting ||8 and a flange ||2 which may be integrally formed with the latch pin |88. A head I3 is provided on the outer end of the latch pin |88 to provide a hold whereby it may be withdrawn to release the fuse cartridge 82.

The lower end of the fuse cartridge 82 is provided with a slight taper I|4 so that, when the fuse cartridge is drawn downwardly through the fuse tube 20 to the position shown in the drawings it can readily depress fhe latch pin |08 un- Itil the groove |0'| is placed in registry therewith. When the fuse cartridge 82 has been drawn to this position, the latch pin |08 snaps into place and securely holds the fuse cartridge 82 in the position shown.

At its lower end the fuse cartridge 82 is provided with a terminal I I5 that is connected by a short length flexible lead IIB to the. ferrule |03. As shown, the flexible lead IIB is provided with a metallic terminal I I having a suitable aperture which permits it to be placed over a stud H8 extending from the ferrule |03. A nut H9 threaded on the stud I|8 serves to securely clamp the terminal I I1 in place.

It will be observed that, once the fuse cartridge 82 is drawn into the latched position, as by exerting a pull on the ilexible lead I6, as is more fully described in my Patent No. 2,226,838, there is no further tension stress applied to the flexible lead IIS. This facilitates the connection of the flexible lead I i6 to the ferrule |03.

When it is desired to remove the fuse cartridge 82, it is only necessary to grasp thehead II 3 and Withdraw the latch pin |08 slightly against the biasing force of the spring III. If the fuse cartridge 82 is unblown, the tension spring 84 will immediately tend to retract the fuse cartridge 82 toward the other end of the fuse tube 20. After the fuse cartridge 82 has blown the outer shell thereof can be readily removed after the flexible lead ||6 is disconnected from the stud I I8 merely by removing the cap 89 and turning the fuse tube 20 up side down and withdrawing the latch pin |08.

Since certain further changes may be made in the foregoing construction and diTerent ernbodirnents of the invention may be made without departing from the scope thereof, it is intended that all matter shown in the accompanying drawings or described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A renewable circuit interrupter comprising, in combination, a tubular housing, a replaceable circuit interrupting device in said housing, latch means extending transversely of said housing and said device for holding the latter in a predetermined position in the former, said latch means extending to a point outside said housing, and means biasing said latch means into latching position.

2. A renewable circuit interrupter comprising,

in combination, a tubular housing, a replaceable circuit interrupting device in said housing, and a biased latch pin movable transversely of said housing and intertting with a recess in said device for latching the latter in a predetermined position in the former, axial movement of said latch pin outwardly of said housing releasing the latching connection.

3. A renewable circuit interrupter comprising. in combination, a tubular housing, a replaceable circuit interrupting device insertable through one end of said housing, latch means extending transversely through said housing for automatically interlocking with said device when it is moved to a predetermined position at the other end of said housing, and means biasing said latch means into latching position.

4. A renewable circuit interrupter comprising, in combination, a tubular housing, a replaceable circuit interrupting device insertable through one end of said housing, and a spring biased latch pin movable transversely of said housing and interiitting with a recess in said device when it is moved to a predetermined position at the other end of said housing, the latching connection being released by axial withdrawal of said latch pin from said recess.

5. A renewable circuit interrupter comprising, in combination, a tubular insulating housing, a replaceable circuit interrupting device insertable through one end 0f said housing, a metallic sleeve at the other end of said housing, latch means extending transversely through said metallic sleeve for automatically interlocking with said device when it is moved to a position within said sleeve, and means biasing said latch means into latclung position.

6. A renewable circuit interrupter comprising, in combination, a tubular insulating housing, a generally cylindrical replaceable circuit interrupting device insertable through one end of said housing and having a radially outwardly opening recess, a metallic sleeve at the other end of said housing having an opening extending transversely through one side, a latch pin slidably mounted within said opening with the inner end adapted to automatically interflt with said recess when said device is moved to a predetermined position within said sleeve, a spring coaxial with said latch pin for biasing the same into latching position, and a head on the outer end of said latch pin limiting inward movement thereof in the absence of said device and providing a hold whereby said latch pin can be withdrawn to permit removal of said device.

HUGH A. TRIPLET'I. 

